King Charles is set to miss the annual Commonwealth Day service on March 11, but will release a video message instead.

In the message, he will hail the spirit of togetherness throughout the 56 member states, the Daily Mirror reports.

The monarch is not expected to end the key fixture in the royal diary due to his ongoing cancer treatment.

Instead, as part of his wish to “remain to be seen” Charles has recorded a special message at Windsor Castle which will be broadcast round the world to mark the event. The theme for this year’s annual meeting is “One Resilient Common Future”.

Royal insiders have said that the monarch wants to express thanks to people around the Commonweath – especially those who have sent well wishes since he shared his cancer diagnosis last month. The King has received more than 7,000 cards and letters urging him to “never give up” as he continues his treatment.

In the King’s absence, Queen Camilla is expected to lead other family members at the service. Prince William is also expected to attend alongside the Queen.

Speaking at last year’s service at Westminster Abbey, the King said: “The Commonwealth has been a constant in my own life, and yet its diversity continues to amaze and inspire me.

“Its near-boundless potential as a force for good in the world demands our highest ambition; its sheer scale challenges us to unite and be bold.”

Commonwealth Day is celebrated by people across Africa, Asia, the Caribbean and Americas, as well as the Pacific and Europe.

This year’s theme reflects the focus of the upcoming Commonwealth Heads of Government Meeting (CHOGM), which will be held in Samoa later this year.